Teasing Nicknames:
*Yanni - In reference to the Greek musician of the same name.
*Jenny Penny
*Jen-Air
*Gender
*Gentle
*Gen-X
*Niffer
*Jennifart
*Jensi
*Winny
*Jeffiner
*Jenny-Fur
*Jennipoo
*Jennipoot
*Jenner
*Jenny-bug
*Jenny Craig
*Jenni
*Nenny
*Neny
*Nena
*Furball
*Jeffinerd
*Jenerator
*Jiffy Sniffer
*Ninny
*Fennifer
*Furry Jen
*Jimmifer
*Genicles
*Jennifer Eckles Had So Many Freckles
*Genever (a Dutch liquor)
*Jenn-Heffer
*Fern
*Jenny Jack Off
*Yen-e-fare
*Fro
*Jefro
*Jenniflirt
*Freakifur
*Jenny Piccolo
*Lalifer
*Jeffner
*Jenn the Hen
*Jenn likes Men
*Feffer
*Jenny-Fred
*G.I. Jen
*Jen-nay
*Jennifurball
*Ferry
*Furry
*Foo Face
*Nini
*J. J.
*J. J. McKay
*Yen Yen
*Jennsy Wennsy
*Jen Da Bend
*Fertilizer
*Jennibean
*Neninerd
*Jenster
*Jenwinder
*FurFur
*Nifer Snifer
*Jemminnifner
*Jen-Jen
*Jennifer Juniper (from the song by Donovan)
*Jenny-Wren
*Jenny Foo Foo
*Jennifeffer
*Fef Ann
Those are from a baby name website...it gives you the drawbacks to picking the name. Some of those are ridiculous, but funny.
http://tools.oxygen.com/babynamer/